1. Industrial Field of the Invention
The present invention relates to a cleaning apparatus for removing filth from an article to be cleaned and a cleaning method, and more specifically, it relates to a manufacturing method for a liquid crystal apparatus having a cleaning process.
2. Description of the Related Art
In various industrial fields, when an objective product is manufactured, filth may adhere to the product, an apparatus having the product, a jig used for manufacturing the product, and so forth. The filth has to be removed from the product and so forth at an appropriate point in time.
For example, when the manufacturing process of a liquid crystal apparatus is supposed, which is an apparatus for displaying the information such as characters, numerals, and patterns by using liquid crystal as a light modulating element, unnecessary liquid crystal may adhere as filth to a finished liquid crystal panel, a liquid crystal apparatus having the liquid crystal panel, a jig used during the manufacturing thereof, and so forth. Such filth is required to be removed at an appropriate point in time.
As a cleaning apparatus for removing filth, an ultrasonic cleaning apparatus using a fluorocarbon solvent is known. In the cleaning apparatus, an article to be cleaned is dipped in a storing vessel storing a fluorocarbon solvent and in which ultrasonic vibration is applied to remove filth from the article to be cleaned.
However, the above-mentioned conventional cleaning apparatus involves problems that an expensive complicated treatment apparatus specially designed for preventing air pollution due to the fluorocarbon and the like is required and an expensive complicated treatment apparatus specially designed for preventing the removed filth from being discharged as waste water is also needed, etc.
Meanwhile, when a liquid crystal apparatus is cleaned, a cleaning apparatus such as an apparatus disclosed in Japanese Unexamined Patent Application Publication No. 7-13115 is adopted. In this apparatus, liquid crystal can be readily separated and removed from cleaning fluid mixing the liquid crystal therewith by cleaning using an ultrafiltration membrane. The cleaning apparatus utilizing the ultrafiltration membrane comprises a cleaning vessel containing cleaning liquid made of an aqueous solution therein and a vibrator arranged in the bottom of the cleaning vessel to be excited by an oscillator, wherein an article to be cleaned such as a glass substrate having liquid crystal adhering thereto is dipped into the cleaning liquid in the cleaning vessel.
The liquid crystal adhering on the surface of the dipped glass substrate is cleaned off the substrate by ultrasonic waves generated by excitation of the vibrator and as well as by detergency of the cleaning liquid. The cleaning liquid mixing the liquid crystal therewith overflows to an annular trough attached to the upper wall of the cleaning vessel to be conveyed to a liquid crystal concentrating vessel via piping. The solution in the concentrating vessel is pressurized by driving of a pump to be fed to the ultrafiltration membrane, to whereby be separated into an emulsionized liquid crystal constituent in the solution and the substantially pure cleaning liquid. Since the separated substantially pure cleaning liquid is recirculated to the cleaning vessel, the reuse of the cleaning liquid and the recovery of the liquid crystal can be achieved.
However, in the cleaning method and the cleaning apparatus, during the using the cleaning liquid repeatedly by separating the cleaning liquid into the liquid crystal in the solution and the substantially pure cleaning liquid by using the ultrafiltration membrane, filthy refuse settles gradually on the internal surface of the ultrafiltration membrane to reduce the separating capacity for the filtered water. Due to the reduced separating capacity, the cleaning liquid circulates in a state of containing filth such as the liquid crystal, so that the cleaning of the cleaning liquid in the cleaning vessel cannot be efficiently achieved. Also, the structure of the cleaning apparatus is insufficient for the cleaning.
In view of the above-mentioned problem, the present invention has been made and it is an object thereof to provide a cleaning apparatus capable of securely and efficiently removing filth from the cleaning liquid repeatedly used by recycling for a long time without using harmful liquid such as a fluorocarbon, moreover by a simplified treatment system, so that an article to be cleaned can be sufficiently cleaned with fresh cleaning liquid having a small amount of filth.
(1) In order to achieve the above-mentioned object, in a cleaning apparatus for removing filth from an article to be cleaned, a cleaning apparatus according to the present invention comprises a cleaning vessel for storing cleaning water used for cleaning the article to be cleaned; a concentrating vessel for storing sewage discharged from the cleaning vessel; an ultrafiltration membrane for receiving the sewage discharged from the concentrating vessel to separate the received sewage into filtered water and concentrated sewage; a waterway line for returning the concentrated sewage discharged from the ultrafiltration membrane to the concentrating vessel; and a backwash filtration system for flushing the ultrafiltration membrane backward with liquid from the filtered water side toward the sewage.
In the structure described above, arbitrary articles may be supposed as an article to be cleaned; for example, a liquid crystal apparatus for displaying the information such as characters, numerals, and patterns by using liquid crystal as a light modulating element; a liquid crystal panel forming a principal part of the liquid crystal apparatus; and a jig used during the manufacturing the liquid crystal apparatus.
Various substances may also be supposed to be the filth; for example, there are unnecessary liquid crystal adhering to external surfaces of the liquid crystal apparatus and the jig, and so forth. The liquid crystal is a substance that cannot be dumped at an arbitrary place without permission.
In a cleaning apparatus according to the present invention, the cleaning is performed with water without using harmful liquid such as a fluorocarbon or a specific detergent, so that there are no worries of external environmental pollution. Since the concentrated sewage discharged from the filtration means is returned to the concentrating vessel, the filth such as liquid crystal cannot be externally discharged, and moreover an amount of waste liquid can be reduced.
Furthermore, since the backwash filtration system is provided in the ultrafiltration membrane, the filth in the circulating cleaning liquid being repeatedly used can be efficiently and securely removed therefrom for a long period. Thereby, an article to be cleaned can be cleaned with substantially pure water at all times. Also, an article to be cleaned can be sufficiently cleaned with fresh cleaning liquid having a small amount of filth.
(2) In a cleaning apparatus for removing filth from an article to be cleaned, another cleaning apparatus according to the present invention comprises a cleaning vessel for storing cleaning water used for cleaning the article to be cleaned; a concentrating vessel for storing sewage discharged from the cleaning vessel; an ultrafiltration membrane for receiving the sewage discharged from the concentrating vessel to separate the received sewage into filtered water and concentrated sewage; and a waterway line for returning the concentrated sewage discharged from the ultrafiltration membrane to the concentrating vessel, wherein a plurality of the ultrafiltration membranes are arranged in parallel with each other in a waterway line starting from the concentrating vessel.
According to this cleaning apparatus, the treatment capacity for filtering the sewage can be increased as much as plural ultrafiltration membranes are provided.
(3) In a cleaning apparatus for removing filth from an article to be cleaned, still another cleaning apparatus according to the present invention comprises a first cleaning unit; and a second cleaning unit, wherein the first cleaning unit is formed according to a cleaning apparatus described in (1) while the second cleaning unit is formed according to a cleaning apparatus described in (2).
According to this structure of the cleaning apparatus, the principal cleaning is performed in the first cleaning unit having the backwash filtration system while rinsing can be performed in the second cleaning unit having plural ultrafiltration membranes, so that the extremely efficient cleaning can be consequently performed.
(4) In a cleaning method for removing filth from an article to be cleaned, a cleaning method according to the present invention comprises the steps of: cleaning the article to be cleaned in a cleaning vessel; storing the sewage discharged from the cleaning vessel in a concentrating vessel; separating the sewage discharged from the concentrating vessel into filtered water and concentrated sewage by an ultrafiltration membrane; returning the concentrated sewage discharged from the ultrafiltration membrane into the concentrating vessel; and flushing the ultrafiltration membrane backward with liquid from the filtered water side toward the sewage by a backwash filtration system.
(5) In a cleaning method for removing filth from an article to be cleaned, another cleaning method according to the present invention comprises the steps of: cleaning the article to be cleaned in a cleaning vessel; storing the sewage discharged from the cleaning vessel in a concentrating vessel; separating the sewage discharged from the concentrating vessel into filtered water and concentrated sewage by an ultrafiltration membrane; and returning the concentrated sewage discharged from the ultrafiltration membrane into the concentrating vessel, wherein a plurality of the ultrafiltration membranes are arranged in parallel with each other in a waterway line starting from the concentrating vessel.
(6) Still another cleaning method according to the present invention comprises the steps of: cleaning the article to be cleaned according to a method described in (4); and cleaning the article to be cleaned according to a method described in (5).
(7) A manufacturing method for a liquid crystal apparatus according to the present invention comprises a cleaning step of an article to be cleaned described in any one of items (4) to (6), wherein the article to be cleaned is an liquid crystal panel or the liquid crystal apparatus.